1. Field of the Invention
The present invention relates to a technique of fabricating a plastic molded article applicable to fabrication of a minute or small structure in the order of μm to nanometers.
2. Description of the Related Art
In the related art, the following techniques are well known for fabricating a plastic molded article (synthesized resin product).
(1) Injection Molding
Specifically, after filling a mold with a melted resin, the melted resin is cooled to obtain a plastic molded article. For example, reference can be made to Japanese Laid Open Patent Application No. 5-185464.
(2) Photolithography
FIG. 21A through FIG. 21C are cross-sectional views schematically illustrating a method of fabricating a plastic molded article by photolithography.
As illustrated in FIG. 21A through FIG. 21C, a thin film formed from a synthesized resin on the surface of a substrate is partially removed by light with a photo resist above the thin film as a photo mask, and a thin film product is obtained to have a two dimensional shape corresponding to the mask, as shown in FIG. 21C.
(3) LIGA Process
FIG. 22A through FIG. 22G are cross-sectional views schematically illustrating a method of fabricating a plastic molded article by a LIGA process.
As illustrated in FIG. 22A through FIG. 22G, lithography is performed by using synchrotron radiation of high directionality, resulting in a high-aspect-ratio molded article having unevenness. After plating and de-molding this molded article having unevenness, a mold is obtained. Then, while this mold is being heated, this mold is pressed against a thermoplastic resin (hot embossing), and a plastic molded article is produced which has a shape corresponding to that of the molded article having unevenness, as shown in FIG. 22G.
(4) Rapid Prototyping Process
FIG. 23A through FIG. 23D are cross-sectional views schematically illustrating a method of fabricating a plastic molded article by a Rapid Prototyping process.
First, three dimensional CAD data of a product to be fabricated are split into thin sectional slices to convert the three dimensional CAD data into contour data. Then, as illustrated in FIG. 23A through FIG. 23D, based on the contour data, an un-cured light curable resin is irradiated by a laser beam to cure the light curable resin step by step, with a thin layer of the light curable resin being irradiated and cured in each step. Then, the un-cured light curable resin is removed after the cured portions of the thin layers are stacked, thus, a solid plastic molded article is obtained, as shown in FIG. 23D.
However, as for the above-described method (1), namely, injection molding, although productivity of the method is excellent, this method is not suitable for experimental production; hence, it is difficult to use this method to form minute shapes.
Concerning the above-described method (2), namely, photolithography, this method requires expensive production equipment, while only being capable of fabricating molded articles not thicker than a few tens μm. Further, this method requires waste disposal accompanying development treatment.
As for the above-described method (3), namely, the LIGA process, the synchrotron radiation equipment is quite expensive, even though the mold is ordered from an outside supplier, the cost is still very high.
Concerning the above-described method (4), namely, the rapid prototyping process, this method is quite effective for produce a complicated three dimensional minute shape, but it is quite time-consuming even when fabricating a single article; especially, productivity of this method is quite poor when fabricating an article of a single shape and large area.